Chapter 20Chapter 20Air PollutionAir Pollution

Overview of Chapter 20Overview of Chapter 20 Atmosphere as a ResourceAtmosphere as a Resource Types and Sources of Air PollutionTypes and Sources of Air Pollution Effects of Air PollutionEffects of Air Pollution Controlling Air Pollution in the USControlling Air Pollution in the US Ozone Depletion in the StratosphereOzone Depletion in the Stratosphere Acid DepositionAcid Deposition Air Pollution Around the WorldAir Pollution Around the World Indoor Air PollutionIndoor Air Pollution

Atmosphere as a ResourceAtmosphere as a Resource

Atmospheric CompositionAtmospheric Composition Nitrogen: 78.08%Nitrogen: 78.08% Oxygen: 20.95%Oxygen: 20.95% Argon: 0.93%Argon: 0.93% Carbon dioxide: 0.04%Carbon dioxide: 0.04%

Ecosystem servicesEcosystem services Blocks UV radiationBlocks UV radiation Moderates the climateModerates the climate Redistributes water in the hydrologic Redistributes water in the hydrologic

cycle cycle

Air Pollution - TerminologyAir Pollution - Terminology

Air PollutionAir Pollution Chemicals added to the atmosphere by Chemicals added to the atmosphere by

natural events or human activities in high natural events or human activities in high enough concentrations to be harmful enough concentrations to be harmful

Two categoriesTwo categories Primary Air PollutantPrimary Air Pollutant

Harmful substance that is emitted directly into Harmful substance that is emitted directly into the atmosphere the atmosphere

Secondary Air PollutantSecondary Air Pollutant Harmful substance formed in the atmosphere Harmful substance formed in the atmosphere

when a primary air pollutant reacts with when a primary air pollutant reacts with substances normally found in the atmosphere or substances normally found in the atmosphere or with other air pollutants, or with sunlight with other air pollutants, or with sunlight

Major Air PollutantsMajor Air Pollutants

Major Classes of Air PollutantsMajor Classes of Air Pollutants Particulate MaterialParticulate Material Nitrogen OxidesNitrogen Oxides Sulfur OxidesSulfur Oxides Carbon OxidesCarbon Oxides HydrocarbonsHydrocarbons OzoneOzone

Particulate MaterialParticulate Material Thousands of different solid or liquid Thousands of different solid or liquid

particles suspended in airparticles suspended in air Includes: soil particles, soot, lead, asbestos, Includes: soil particles, soot, lead, asbestos,

sea salt, and sulfuric acid droplets sea salt, and sulfuric acid droplets DangerousDangerous

May contain materials with toxic/carcinogenic May contain materials with toxic/carcinogenic effectseffects

Small particles can become lodged in lungsSmall particles can become lodged in lungs

Nitrogen and Sulfur OxidesNitrogen and Sulfur Oxides Nitrogen OxidesNitrogen Oxides

Gases produced by the chemical interactions Gases produced by the chemical interactions between atmospheric nitrogen and oxygen at between atmospheric nitrogen and oxygen at high temperaturehigh temperature

Greenhouse gases that cause difficulty Greenhouse gases that cause difficulty breathingbreathing

Sulfur OxidesSulfur Oxides Gases produced by the chemical interactions Gases produced by the chemical interactions

between sulfur and oxygen between sulfur and oxygen Causes acid precipitationCauses acid precipitation

Carbon Oxides and Carbon Oxides and HydrocarbonsHydrocarbons Carbon OxidesCarbon Oxides Gases carbon monoxide (CO) and carbon Gases carbon monoxide (CO) and carbon

dioxide (COdioxide (CO22) ) Greenhouse gasesGreenhouse gases

HydrocarbonsHydrocarbons Diverse group of organic compounds that Diverse group of organic compounds that

contain only hydrogen and carbon (ex: CHcontain only hydrogen and carbon (ex: CH44- - methane)methane)

Some are related to photochemical smog and Some are related to photochemical smog and greenhouse gasesgreenhouse gases

OzoneOzone Tropospheric OzoneTropospheric Ozone

Man- made pollutant in the lower atmosphereMan- made pollutant in the lower atmosphere Secondary air pollutantSecondary air pollutant Component of photochemical smogComponent of photochemical smog

Stratospheric OzoneStratospheric Ozone Essential component that screens out UV Essential component that screens out UV

radiation in the upper atmosphereradiation in the upper atmosphere Man-made pollutants (ex: CFCs) can destroy Man-made pollutants (ex: CFCs) can destroy

itit

Sources of Outdoor Air PollutionSources of Outdoor Air Pollution

Two main Two main sourcessources TransportationTransportation IndustryIndustry

Intentional Intentional forest fires is forest fires is also highalso high

Urban Air PollutionUrban Air Pollution

Photochemical Smog (ex: Los Photochemical Smog (ex: Los Angeles below)Angeles below) Brownish-orange haze formed by Brownish-orange haze formed by

chemical reactions involving sunlight, chemical reactions involving sunlight, nitrogen oxide, and hydrocarbons nitrogen oxide, and hydrocarbons

Formation of Photochemical Formation of Photochemical SmogSmog

Sources of Smog in Los AngelesSources of Smog in Los Angeles

Effects of Air PollutionEffects of Air Pollution

Low level exposureLow level exposure Irritates eyesIrritates eyes Causes inflammation of respiratory tractCauses inflammation of respiratory tract

Can develop into chronic respiratory Can develop into chronic respiratory diseasesdiseases

Children and Air PollutionChildren and Air Pollution Greater health threat to children than Greater health threat to children than

adultsadults Air pollution can restrict lung developmentAir pollution can restrict lung development Children breath more often than adultsChildren breath more often than adults

Children who live in high ozone areas are Children who live in high ozone areas are more likely to develop asthmamore likely to develop asthma

Without Without Electrostatic Electrostatic precipitatorprecipitator

With Electrostatic With Electrostatic precipitatorprecipitator

Controlling Air Pollution Controlling Air Pollution Smokestacks with Smokestacks with

electrostatic electrostatic precipitator (right)precipitator (right)

Controlling Air PollutionControlling Air Pollution

Smokestacks with Smokestacks with scrubbers (right)scrubbers (right)

Particulate material Particulate material can also be controlled can also be controlled by proper excavating by proper excavating techniquestechniques

Controlling Air PollutionControlling Air Pollution Gasoline vapors are a major source of VOC’s Gasoline vapors are a major source of VOC’s

(volatile organic compounds), which are (volatile organic compounds), which are extremely harmful!extremely harmful!

Phase I Vapor Recovery System for gasoline Phase I Vapor Recovery System for gasoline involves collecting unburned vapors from involves collecting unburned vapors from underground tanks at gas stations!underground tanks at gas stations!

The Clean Air ActThe Clean Air Act Authorizes EPA to set limits on amount of Authorizes EPA to set limits on amount of

specific air pollutants permittedspecific air pollutants permitted Focuses on 6 pollutants:Focuses on 6 pollutants:

lead, particulate matter, sulfur dioxide, lead, particulate matter, sulfur dioxide, carbon monoxide, nitrogen oxides, and ozonecarbon monoxide, nitrogen oxides, and ozone

Act has led to decreasesAct has led to decreases

The Clean Air ActThe Clean Air Act

Urban Air QualityUrban Air Quality

Other Ways to Improve Air Other Ways to Improve Air QualityQuality

Reduce sulfur content in gasoline from Reduce sulfur content in gasoline from its current average of 330 ppm to 30 its current average of 330 ppm to 30 ppmppm Sulfur clogs catalytic convertersSulfur clogs catalytic converters

Require federal emission standards for Require federal emission standards for all passenger vehiclesall passenger vehicles Including SUVs, trucks and minivansIncluding SUVs, trucks and minivans

Require emission testing for all vehiclesRequire emission testing for all vehicles Including dieselIncluding diesel

Ozone Depletion in Ozone Depletion in StratosphereStratosphere Ozone Protects earth from UV radiationOzone Protects earth from UV radiation

Stratospheric Ozone:Ozone (O3) forms a layer in the stratosphere,

measured in Dobson Units (typically 260 DU near the equator, higher toward the poles)

Ozone is created when UV radiation strikes molecules of Oxygen (O2) in the stratosphere, and splits (dissociates) them into free O atoms, which then quickly combine to form ozone.

1. O2 + UV -> O + O

2. O + O2 -> O3

Stratospheric Ozone:Ozone can then be destroyed & reformed

by the same UV radiation, in a natural cycle as follows:

3. O3 + UV -> O2 + O

4. O + O2 -> O3 as above Ozone levels peak at about 25 KM above

Earth’s surface. Stratospheric Ozone – absorbs 99% of

UV if left at “natural” levels

Three Categories of UV Radiation:

UV-C UV-B UV-A

Size of Wavelength:

200-280 280-320 320-400

Absorption:Fully absorbed

by O2 & O3Most is absorbed

by O3Mostly reaches

surface

Results Associated

with Exposure:

Serious cell mutation, cancer

Skin cancer & cataracts,

phytoplankton kills

Produces Vitamin D

with background

exposure levels

Ozone Depletion in Ozone Depletion in StratosphereStratosphereOzone thinning/holeOzone thinning/hole

First identified in 1985 over First identified in 1985 over AntarcticaAntarctica

Caused by human-Caused by human-produced produced bromine bromine and and chlorinechlorine containing containing chemicals. (Halogens)chemicals. (Halogens)

Ex: CFCsEx: CFCs propellants used for propellants used for

aerosol cans (no longer in aerosol cans (no longer in use)use)

coolants in refrigeration coolants in refrigeration (Freon)(Freon)

foam (Styrofoam) foam (Styrofoam) blowing agents in blowing agents in

insulationinsulation solventssolvents

How does Chlorine (CFC) destroy Ozone?Chemical reaction creates a catalyst!1.CCl3F + UV Cl + CCl2F

2.Cl + O3 ClO + O2

3.ClO + O Cl + O2

Ozone Depletion in Ozone Depletion in StratosphereStratosphere Hole over Antarctica requires Hole over Antarctica requires three three

conditionsconditions:: The development of the The development of the circumpolar vortexcircumpolar vortex

- a mass of frigid air that circulates around - a mass of frigid air that circulates around the southern polar region the southern polar region

The formation of The formation of polar stratospheric polar stratospheric cloudsclouds – masses of ice crystals onto which Cl – masses of ice crystals onto which Cl and Br can settle. This enables Cl and Br to and Br can settle. This enables Cl and Br to destroy ozonedestroy ozone

Sunlight just returning to polar region (occurs Sunlight just returning to polar region (occurs in spring in the S. hemisphere (Sept. – Oct.) in spring in the S. hemisphere (Sept. – Oct.) which triggers the release of the Cl and Br which triggers the release of the Cl and Br from the polar stratospheric cloudsfrom the polar stratospheric clouds

Effects of Ozone DepletionEffects of Ozone Depletion

Higher levels of UV-Higher levels of UV-radiation hitting the radiation hitting the earthearth Eye cataractsEye cataracts Skin cancer (right)Skin cancer (right) Weakened immunityWeakened immunity

May disrupt May disrupt ecosystemsecosystems

May damage crops May damage crops and forestsand forests

Recovery of Ozone LayerRecovery of Ozone Layer Montreal Protocol (1987)Montreal Protocol (1987)

Reduction of CFCsReduction of CFCs Started using HCFCs (greenhouse gas)Started using HCFCs (greenhouse gas)

Phase out of all ozone destroying Phase out of all ozone destroying chemicals is underway globallychemicals is underway globally

Satellite pictures in 2000 indicated that Satellite pictures in 2000 indicated that ozone layer was recoveringozone layer was recovering

Full recovery will not occur until 2050Full recovery will not occur until 2050

Acid DepositionAcid Deposition Sulfur dioxide and nitrogen dioxide Sulfur dioxide and nitrogen dioxide

emissions react with water vapor in the emissions react with water vapor in the atmosphere and form acids that return to atmosphere and form acids that return to the surface as either dry or wet the surface as either dry or wet deposition deposition

pH scalepH scale

How Acid Deposition DevelopsHow Acid Deposition Develops

Effects of Acid DepositionEffects of Acid Deposition

Declining Declining Aquatic Animal Aquatic Animal PopulationsPopulations

Thin-shelled Thin-shelled eggs prevent eggs prevent bird bird reproductionreproduction Calcium is Calcium is

unavailable in unavailable in acidic soilacidic soil

Forest declineForest decline

Acid Deposition and Forest Acid Deposition and Forest DeclineDecline

Air Pollution Around the WorldAir Pollution Around the World Air quality is deteriorating rapidly in Air quality is deteriorating rapidly in

developing countries developing countries Developing countries have older carsDeveloping countries have older cars

Shenyang, ChinaShenyang, China Residents only see sunlight a few weeks each Residents only see sunlight a few weeks each

yearyear 5 worst cities in world5 worst cities in world

Beijing, China; Beijing, China; Mexico City, Mexico; Mexico City, Mexico; Shanghai, China; Shanghai, China; Tehran, Iran;Tehran, Iran; Calcutta, India Calcutta, India

Case-In-Point Air Pollution in Case-In-Point Air Pollution in Beijing and Mexico CityBeijing and Mexico City

Beijing (left)Beijing (left) Mexico City (above)Mexico City (above)

Global Distillation EffectGlobal Distillation Effect

Long Distance Transport of Air Long Distance Transport of Air PollutantsPollutants

Indoor Air PollutionIndoor Air Pollution

Pollutants can Pollutants can be 5-100X be 5-100X greater than greater than outdoorsoutdoors

Radon, cigarette Radon, cigarette smoke, carbon smoke, carbon monoxide, monoxide, nitrogen dioxide, nitrogen dioxide, formaldehyde formaldehyde pesticides, lead, pesticides, lead, cleaning cleaning solvents, ozone, solvents, ozone, and asbestos and asbestos

Indoor Air Pollution - RadonIndoor Air Pollution - Radon